Feeder motor failure after 1 Week


#1

The feeder motor in my Mooz2 has failed less than a week in.

It no longer has enough traction to pull filament; It failed during a print and I can no-longer get it to pull filament off the spool.

I am unsure what has caused this, but despite best attempts at clogging the print-head only extrudes with manual force applied down on the filament from outside the print-head.

Picture and Video gallery Gallery here:

64 new photos · Album by Joel Wirāmu Pauling

#2

Beware - when attempting to disassemble the motor/feeder/printhead assembly there are several Hex/Torque screws affixing the Motor assembly to the outer housing.

These are from soft alloy and small allen/drivers will strip these as they are over torqued. This appears to be a deliberate design choice.

Looking down the feeder barell now I have the extruder head out of the way I think I can see the design fault.

There is only a single Teethed cog that rotates with the Motor rather than a dual action push/pill through design like on ultimaker etc.

The external ‘release’ button is a direct sprung set of teeth that pushes the filament against the single rotating cog.

The teeth on this cog are worn down (it’s probably the same shitty alloy as in the hex screws attaching the motor to the housing). After a while ( a week/ and little less than a few hundred grams of print), the teeth will warp on the cog, effectively making it useless.

Until I can borrow a friends bench drill to tap out the stripped screws my mooz is now a pile of junk.

If we had board schematics I could easily replace the print head with any number of viable replacements.


#3

Oh, man - I’m so sorry to hear that. You’re super helpful on this forum - I hope you stick around, and it sucks that you are having such a crappy experience. And yes, I’m nervous that my Mooz will fail after a few more prints.

I hope someone from Dobot gets on this right away - they should treat you like a superstar, with all the effort you’re willing to put into their product, which it’s becoming more and more clear isn’t quite finished. :frowning:


#4

So far I am getting dead silence both on forum and via e-mail. It is Lunar New Year tho; so I’ll give it another week, plus I am in the process of moving into a new house. I was hoping the mooz would help with printing stuff for that… oh well, should have bought an Anet or Creality.

Especially pissed off they are shipping binary GPL code and have made zero attempts to provide source code. I know a few Reprap and Marlin Developers and it really pisses me off to see their work get ripped of in a product with zero credit given.


I’ve just fully stripped the motor assembly after some improvising to get the hex screws out and realigned the cog/sping release. Unfortunately to no gain.

I think the stepper motor is likely cheap and has just overheated/lost torque, either that or the aforementioned cog teeth stripping.


#5

For reference the Stepper Motor company is Baolong Motor : http://en.baolongmotor.com/product/NEMA17-Linear-Hybrid-Stepper-Motor.html

Also it appears to be mislabeled as 1.5A it’s actually 1.3A


#6

Ugh. Yeah, such a bummer. I saw your post on the GPL redist, they need to address this. It gives the impression of a shady company with questionable ethics.

In the end, the Mooz feels like it’s all about the bargain - I mean, a functional 3-in-1 for the Kickstarter price - you can’t get that deal anywhere else. So I figured there would probably be a certain amount of tinkering required. This is my first home printer, so I wanted to use it as a learning piece, and assumed I’d have to futz around with it a lot. I certainly am not expecting it to fail in a week.

So far I’ve been printing for a few days, have gotten maybe a dozen successful prints, and at least a dozen more with poor adhesion. Thanks to your gcode start fix, I seem to be getting successful prints a lot more frequently, so just hoping not to mess anything up, as it sounds like there are some delicate bits.

Again - as a community member, want to thank you for all your contributions. I really hope they take care of you - if they’re a smart company, they’ll realize what an asset they have with you. Community members who actively solve problems for others are a gold mine, and if they’re smart, they’ll answer your email and make you a moderator of the forum! Anything they can to make you happy! Someone like you, knowledgeable and engaged, and willing to put in effort to fix problems, can actively drive sales - or actively kill them.


#7

The problem is it’s not really.

Inc shipping to NZ the Mooz2 kit ended up being 600$ NZD off the KS

CR10 Kit (inc shipping)
300$

Or a Reprap/Prusa save another 50$ at 250$

Add a CNC head ~100$

Add a Lazer Head ~80$

Add a couple of rolls of good pla+ ~80$

So for same price I likely could had something with a bigger build volume same set of features, an Open and Supportable set of parts and decent community. Not to mention a firmware that actually works and is getting better everyday.

Mooz sold itself on High precision; so far I’ve seen no evidence it’s capable of what the spec overview said it can vs what event Anet A8 can do (and that’s a sub 200$ kit)


#8

Aenertia, the Cog with the “grove” for filament to fit in, IIRC from when I dissassembled mine should have quite visible teeth, I think you just have bad batch that wasn’t produced properly because it looks, from the photo at least, it hasn’t got any teeth rather than being worn down, and PLA shouldn’t be able to wear it down either…

All the steppers are Baolong motors, the rating probably isn’t wrong, they probably just have a custom order rather than stock. Still, they are only $5 motors so would not be too surprised.

I dont think the stepper is the issue, mine has quite surprising pulling potential when I was holding filament it as it printed. I would suspect the teeth as you say.

I think comparing it to some of the other printers which don’t have such a solid construction isn’t a fair comparison, not to mention the list of common issues people have with those printers, including quality and so on… I can however see your frustration though due to such issues.


#9

The CR10 is pretty solid also; it has Metal support crossbar with 2 Z driver motors similar to what Mooz has; they use external rollers on the Solid Rails vs completely enclosed turning screw. So the CR10 is absolutely a fair comparison.

As I said, the Mooz’s ultimate success is Dependant on them opening up and contributing back to the communities they have used in the project. It’s also a Legal requirement.

The whole extruder assembly is relatively basic ; I think having it enclosed actually is part of the problem; the Cog has teeth still and the reason I suspect it’s the Motor is because even after manually ‘catching the filament’ in the cog with the release spring. Neither advancing the stepper or reversing it exterts any appreciable force on the filament. The Cog appears to be grabbing (and leaving teeth marks) still.


#10

Did you see if that little key screw in the stepper gear is tightened up?


#11

Yes; I am aware of said screw.


#12

From the pictures I wouldn’t say it’s the 'worn gears causing it to not feed. I agree it’s a design flaw to only have the one gear, but the ‘wear’ as pictured is most definitely not the cause.

I’ve had two separate issues with the feeder, first it seems the head got clogged and the feeder kept feeding clogging up the gear and the release button. And then when I cleaned it and reprinted something else backfired and the nozzle unscrewed itself and somehow ended up with pla everywhere!


#13

Yeah - I wish it was clogging I saw when I opened it up. It extrudes fine if I push down on the filament, and no sign of PLA in the Extruder feeder mechanism.

I think I could probably jury rig a Mk10 Extruder from a Prusa i3 in there; but without schematics I am weary of drop-in replacing anything on the mooz. I am still leaning toward stepper motor failure at this point tho, the gear doesn’t look worn you are right.


#14

I’ve got some pics here of my issue

I’m not an expert by any standards but it feels like the quality of the printer was overhyped due to the “solid” construction and then they skimped out a bit on the actual components.

I haven’t tried the laser or cnc yet. Might redeem itself


#15

By no longer has enough traction you mean motor skip steps or it doesn’t feed at all? If it is step missing, it will produce loud click noise during feeding.
Firstly don’t assemble the extruder up and check whether all the components are working nomally, the fans and the motor, insert the filament into the gear, use the touch pad to feed, exert slight force and check if there are problems with the motor and the gear.
If the motor is fine, your problem could be caused by clooged filament barrel and nozzle.
We provided video about how to maintain the printing head on www.dobot.cc, please follow it strictly to prevent filament leakage after reassembling.


#16

The problem could be caused to high retraction speed, retraction distance and too high ambient temperature.


#17

Likely - the Filament and hotend are very oozy, retraction is required to be high to avoid globing.

Ambient temp here is lower than 20Deg and there is an AC unit blowing over the Mooz.

If the Stepper has failed due to heat issues, then it’s entirely due to design of the head housing.

The filament supplied melts much lower than 200Deg so have been running the hot end low (193-195).

But yes retraction set between 3 and 5mm and speed around 20-40mm. This seems pretty normal to me for an oozy feeder.


#18

This was the process I was using. Motor has lost toque, as evidenced by the not feeding at all. Still some traction but not enough to feed/retract any more.


#19

It was an answer to karrotbear’s issure.


#20

Make sure the motor is connected to the right socket and the temperature sensor must be connected before reboot when testing the motor. If it is a motor failure problem, our after-sale support team will help you after Chinese New Year, sorry for the trouble.